Abstract

We report nanometer-scale fabrication on metalthin films using ablation by femtosecond laser pulses, with Bessel beam profiles. Choosing the laser fluence around ablation threshold allows control of the structure size below the diffraction limit. We show that using Bessel beams has several advantages. Bessel beams have focal spot sizes insensitive to longitudinal position, which significantly relaxes alignment constraints. Tighter foci are easier to generate, less costly, and less prone to aberrations. Scaling the method to shorter wavelengths, and hence increasing the resolution is also straightforward. By using the proposed method, we generate structures with resolution below 200 nm.

Received 12 October 2011Accepted 28 December 2011Published online 18 January 2012

Acknowledgments:

This work was supported by Scientifc and Technological Research Council of Turkey (TUBITAK, Grant Number 110T330), Istanbul Technical University Mechatronics Center for Education and Research (ITU MEAM), Istanbul Technical University Scientific Research Projects Department (ITU BAP, project number 33852), and Turkish Academy of Sciences (TUBA GEBIP). We are also grateful to O. Gurlu of ITU and National Nanotechnology Research Center (UNAM) for their help with sample preparation and analysis.